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[Ru3(CO)12] reacts with 2,5-bis(2-thienyl)-1-phenyl-phosphole (btpp) in refluxing CH2Cl2 to afford mono-, di- and trisubstituted derivatives: [Ru3(CO)11(btpp)] (1), [Ru3(CO)10(btpp)2] (2) and [Ru3(CO)9(btpp)3] (3), as well as the unique ruthenacyclopentadiene compound [Ru2(CO)4(μ-CO)(btpp)(μ-η1:η1:η4-C16H14S2)] (4), whose structure was confirmed by single-crystal X-ray crystallography. The photolysis of 3 in CH2Cl2 leads to the novel complex [Ru(CO)2(btpp)(η4-COC16H14S2)] (5), such that its single-crystal structure reveals the fragmentation of the triruthenium cluster, leading to a cyclopentadienone ruthenium complex. The synthesis of both ruthenacyclopentadiene (4) and cyclopentadienone (5) ruthenium complexes opens access to inaccessible ligand systems with π-conjugated structures that might be interesting in the development of new organometallic materials. The reaction of [Os3(CO)10(CH3CN)2] with btpp in refluxing CH2Cl2 affords mono- and disubstituted clusters: [Os3(CO)11(btpp)] (6) and [Os3(CO)10(btpp)2] (7). The trisubstituted complex [Os3(CO)9(btpp)3] (8) is formed by reaction of compound 7 with equimolar amounts of trimethylamine oxide and btpp. In contrast to 3, no fragmentation product was detected from the triosmium carbonyl cluster [Os3(CO)9(btpp)3] (8). A comparative analysis of the UV-vis spectra of [Ru3(CO)9(btpp)3] (3) and [Os3(CO)9(btpp)3] (8) suggests that their different photochemical reactivities might not only be affected by the energetics of their electronic transitions, but also by a combination of subsequent metal–ligand and metal–metal intramolecular interactions.

International audience; A series of complexes including sigma3,lambda3-P-modified PAH as a ligand have been prepared showing that the ligand possesses a classical “phosphine like” reactivity. The use of different metals (Pd(II), Cu(I), Re(I), Au(I)) having different coordination number allows to tune the optical properties of the complexes, which is dominated basically by the electronic transitions of the ligand itself. The study of the solid state properties by mean of X-ray diffraction also shows that the combination of coordination chemistry and pi-stacking interactions between the PAH ligand allows to obtain a great diversity of solid state structures.

International audience; A variety of dirhenium carbonyl complexes containing π-conjugated phosphole derivatives were obtained from reaction of [Re2(CO)8(CH3CN)2] with each of the following phospholes: 2,5-bis(2-thienyl)-1-phenylphosphole (btpp), 2,5-bis(2-pyridyl)-1-phenylphosphole (bpypp) and 1,2,5-triphenylphosphole (tpp). The π-conjugated phospholes were found to behave as two-, four- or six-electron donor ligands via σ or σ-π interactions with the metal centers, presenting bridging or chelating coordination modes as determined by spectroscopic methods and single crystal X-ray diffraction analysis. Metal-metal bond cleavage was evidenced when btpp was used, leading to a mono-substituted mononuclear complex. Variable-temperature 1H NMR studies for σ,π-complexes showed a fluxional behavior due to the restricted rotation around the P–C and C–C bonds of the 1,2,5-trisubstituted phosphole ring.

International audience; Monometallic gold(I)-alkynyl-helicene complexes (1a,b,) and bimetallic gold(I)-alkynyl-helicene architectures featuring the presence (2a,b) or absence (3a,b) of aurophillic intramolecular interactions were prepared by using different types of phosphole ligands (mono-phosphole L1 or bis-phospholes L2,3). The influence of the Au(I) d10-metal center(s) on the electronic, photophysical and chiroptical properties of these unprecedented phosphole-gold(I)-alkynyl-helicene complexes were examined. Experimental and theoretical results highlight the importance of ligand-to-ligand-type charge transfers and the strong effect of presence or absence of Au(I)-Au(I) interactions in 2a,b.

International audience; The reaction between a preassembled CuI bimetallic molecular clip with a short intermetallic distance and a series of fully aliphatic cyano-capped ditopic linkers with increasing lengths was investigated. It is shown that, depending on the length of the ditopic linkers, the rational design of unprecedented supramolecular compact metallacycles containing fully aliphatic walls is possible. The specific preorganized molecular arrangement of the molecular clip used favors stabilizing interlinker London dispersion interactions, which allow, as the length of the linkers increases, the selective formation of discrete compact metallacycles at the expense of 1D coordination polymers. The generalizability of this approach was demonstrated by the reaction of fully aliphatic cyano-capped linkers with two other types of preassembled CuI bimetallic molecular clips that also had short intermetallic distances.

International audience; The reaction of [Re2(CO)8(CH3CN)2] with bis(2-thienyl)biphosphole in refluxing n-octane affords the complex [Re(CO)3(η5-PC16H14S2)] (1) where cleavage of the Re–Re and P–P bonds occurs; its molecular structure confirms the formation of a rhenium mononuclear compound with a η5-coordinated phospholyl unit and three carbonyl groups oriented in a tripod. On the other hand, bis(2-thienyl)biphosphole reacts with [Ru3(CO)12] in refluxing cyclohexane to affording two new compounds [Ru3(CO)9(μ:η1:η5-PC16H13S2)] (2) and [Ru4(CO)13(μ:η1-PC16H14S2)2] (3). Spectroscopic data and theoretical studies of 2 suggest the formation of an open Ru3 cluster with two metal–metal bonds bridged by a (η1:η5-PC16H13S2) unit and a C-H bond activation of one of the thienyl substituents. X-ray structure of 3 reveals a novel tetranuclear ruthenium cluster containing 13 terminal carbonyl ligands and two phospholyl units coordinated as μ-phosphide.

Reactions between the U-shaped binuclear Cu(I) complex A that bears short metal-metal distances and the cyano-capped monotopic π-conjugated ligands 1-5 that carry gradually bulkier polyaromatic terminal fragments lead to the formation of π-stacked supramolecular assemblies 6-10, respectively, in yields of 50-80 %. These derivatives have been characterized by multinuclear NMR spectroscopic analysis and X-ray diffraction studies. Their solid-state structures show the selective formation of U-shaped supramolecular assemblies in which two monotopic π-conjugated systems present large (6, 7, and 9) or medium (8 and 10) intramolecular π overlap, thus revealing π-π interactions. These assemblies self-organize into head-to-tail π-stacked dimers that in turn self-assemble to afford infinite columnar π stacks. The nature, extent, and complexity of the intermolecular contacts within the head-to-tail π-stacked dimer depend on the nature of the terminal polyaromatic fragment carried by the cyano-capped monotopic ligand, but it does not alter the result of the self-assembling process. These results demonstrate that the dinuclear molecular clip A that bears short metal-metal distances allows selective supramolecular assembly processes driven by the formation of intra- and intermolecular short π-π interactions in the resulting self-assembled structures; thus, demonstrating that their shape is not only dictated by the symmetry of the building blocks. This approach opens perspectives toward the formation of extended π-stacked columns based on dissymmetrical and functional π-conjugated systems.

Glioblastoma, an aggressive brain tumor, has a poor prognosis and a high risk of recurrence. An improved chemotherapeutic approach is required to complement radiation therapy. Gold(I) complexes bearing phosphole ligands are promising agents in the treatment of cancer and disturb the redox balance and proliferation of cancer cells by inhibiting disulfide reductases. Here, we report on the antitumor properties of the gold(I) complex 1-phenyl-bis(2-pyridyl)phosphole gold chloride thio-β-d-glucose tetraacetate (GoPI-sugar), which exhibits antiproliferative effects on human (NCH82, NCH89) and rat (C6) glioma cell lines. Compared to carmustine (BCNU), an established nitrosourea compound for the treatment of glioblastomas that inhibits the proliferation of these glioma cell lines with an IC50 of 430μM, GoPI-sugar is more effective by two orders of magnitude. Moreover, GoPI-sugar inhibits malignant glioma growth in vivo in a C6 glioma rat model and significantly reduces tumor volume while being well tolerated. Both the gold(I) chloro- and thiosugar-substituted phospholes interact with DNA albeit more weakly for the latter. Furthermore, GoPI-sugar irreversibly and potently inhibits thioredoxin reductase (IC50 4.3nM) and human glutathione reductase (IC50 88.5nM). However, treatment with GoPI-sugar did not significantly alter redox parameters in the brain tissue of treated animals. This might be due to compensatory upregulation of redox-related enzymes but might also indicate that the antiproliferative effects of GoPI-sugar in vivo are rather based on DNA interaction and inhibition of topoisomerase I than on the disturbance of redox equilibrium. Since GoPI-sugar is highly effective against glioblastomas and well tolerated, it represents a most promising lead for drug development. This article is part of a Special Issue entitled: Thiol-Based Redox Processes.

International audience; new angle: The insertion of a 2,2′-biphosphole subunit into π-conjugated systems offers a new way to control the HOMO-LUMO gap. Tuning of the dihedral angle (θ) between the two phosphorous heterocycles, either by metal coordination or covalent bonding through the P substitution can lead to control of the band gap. These new π-conjugated systems can be used as emitting materials in white organic light-emitting devices (WOLEDs).

International audience; Acetylacetonato-platina[6]- and -platina[7]helicenes have been prepared from 2-pyridyl-substituted benzophenanthrene ligands by following a two-step cycloplatination reaction. The photophysical properties (UV-visible absorption and emission behavior) and chiroptical properties (circular dichroism and molar rotation) of the resolved enantiomers have been measured. These metallahelicenes constitute a novel family of easily accessible helicene derivatives that exhibit large and tuneable chiroptical properties that can be rationalized theoretically and compared to the parent [6]- and [7]carbohelicenes. Furthermore, they are red phosphors at room temperature and their large chiroptical properties can be modulated by oxidation of the metal center to Pt(IV). Hetero- and homochiral diastereomeric bis(metallahelicene)s that possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands have also been prepared. It is shown that the heterochiral (P,M)-bis(Pt(III)-[6]helicene) 9a(1) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene) 9a(2). Spectral assignments and an analysis of the optical rotation of these systems were made with the help of time-dependent density functional theory. The calculations highlight the contributions of the metal centers to the chiroptical properties. For 9a(1) and 9a(2), σ-π conjugation between the helicenes and the Pt-Pt moiety may contribute strongly to the optical rotation and electronic circular dichroism.

International audience; The reaction of the [{CpMo(CO)(2)}(2)(μ,η(2):η(2)-P(2))] (Cp=cyclopentadienyl) metallo-ligand 2 with pre-organized Cu(I) bi- and trimetallic precursors afforded new coordination complexes with unprecedented coordination modes for a Mo(2)P(2) complex. Variable-temperature solution and solid-state (31)P NMR spectroscopy measurements were performed and X-ray diffraction studies revealed an η(2):η(1) coordination mode for the Mo(2)P(2) unit of 2 in the Cu(I) bimetallic complexes 3 and 4. DFT calculations were carried out to highlight the bonding situation of this unprecedented coordination mode in the Cu(I) bimetallic compound 3. It is built up from a side-on coordination of the P-P σ bond to one copper ion and from the interaction of the lone pair of one phosphorus atom with the second copper ion. The remaining available lone pair of the second phosphorus atom can be involved as well to interact with an additional metal centre, as evidenced in the Cu(I) trimetallic compound 5 in which an η(2):η(1):η(1) coordination mode of the ligand 2 is observed. Derivative 3 can be used as a molecular clip to obtain discrete π-stacked dimers through a ligand exchange reaction between acetonitrile ligands and cyano-capped π-conjugated systems, indicating the stability of the new η(2):η(1) coordination mode.

The syntheses, spectroscopic characterizations, and X-ray structures of two new N,P,N-ligands 1 and 2 are described. These ligands are based on a central 2,5-substituted phosphole ring and have, respectively, two 4-pyridyl moieties, or one 4-pyridyl moiety and one 2-pyridyl moiety as substituents. The coordination chemistry of these ligands has been investigated. A Au(I)-complex 5 bearing ligand 1 as a P-donor and a Pt(II) complex 6 featuring ligand 2 as a P,N-chelate were obtained. Complex 6 spontaneously evolves to complex 7 bearing a 2-phospholene ring. Spectroscopic characterizations for complexes 5–7 as well as the X-ray crystal structure of 7 are described. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:339–347, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20687

The synthesis and reactivity of diazomethylenephosphoranes 2, bis(phosphanyl)carbodiimide 5, and N-phosphanyl nitrilimine 10 are presented. The synthesis of transient N-phosphanyl isodiazirine 19 and its rearrangement into 1,3,2λ5-diazaphosphete 20 are discussed.

The solid state structure of a Cu(I) cluster bearing bridging phosphane ligands is described. This Cu4 cluster results from a formal Cl-abstraction of the CH2Cl2 solvent. This derivative is the first example of a multinuclear Cu(I) complex bearing bridging phosphane ligands in which the Cu(I) centers have different coordination geometries. The four Cu(I) ions participate in metallophilic interactions within this cluster. Interestingly, despite the gross molecular structure being highly dissymmetrical, the μ-P atoms bridge symmetrically the metal centers.

International audience; Enantiopure metallahelicenes have been prepared by cyclometalation of 2-pyridyl-substituted benzophenanthrenes followed by resolution using chiral HPLC. They are red phosphors at room temperature and their chiroptical properties can be modulated by oxidation of the metal center to the oxidation state IV.

Bis(2-pyridyl)phosphole 1 reacted with Cu(I) sources giving rise to dicationic or neutral dimers 2,3. In these derivatives, 1 acts as a 1kappaN:1,2kappaP:2kappaN donor with a symmetrically bridging P centre. X-ray diffraction studies of these species revealed no constraint due to the unusual coordination mode of the P donor. A comparative study with a monometallic Cu(I) complex in which 1 acts as a P,N chelate is presented. The acetonitrile ligands of the dicationic complex 2 can be displaced by a variety of donors. Bipyridine (bipy) acts as a chelating donor, while 1,1'-bis(diphenylphosphino)methane (dppm) and bis(2-pyridyl)phosphole 1 behave as bridging ligands. By using dppm and 1, the complexes arising from the stepwise displacement of the acetonitrile ligands of complex 2 can be isolated. X-ray diffraction studies performed on these novel complexes revealed that the P centre can easily switch from a bridging to a semibridging coordination mode. Of particular interest, within the same unit cell, complexes with P centres exhibiting bridging and semibridging coordination modes are observed. This switching can be induced by weak effects such as a different conformation of the incoming ligand. Cu(I) dimers assembled by 1 are air-stable derivatives that are not water sensitive. Hydrolysis of the PF(6) (-) counterion occurs under drastic conditions and results in the formation of a PO(2)F(2) fragment coordinated to a Cu(I)-1 fragment.

International audience; The unsaturated cluster [Os3(μ-H)2(CO)10] reacts with a variety of π-conjugated phosphole ligands: 2,5-bis(2-thienyl)-1-phenylphosphole, 2,5-bis(2-pyridyl)-1-phenylphosphole, and 1,2,5-triphenylphosphole, to give the monosubstituted [Os3(μ-H)(H)(CO)10(P)] and [Os3(μ-H)2(CO)9(P)] derivatives. Variable-temperature 1H NMR studies for the decacarbonyltriosmium complexes show that the hydride ligands undergo fluxional behavior and its decarbonylation gave the nonacarbonyl unsaturated species with equivalent hydrides. An X-ray crystallographic analysis of [Os3(μ-H)2(CO)9(P)] (2b) (P = 1,2,5-triphenylphosphole) is reported. From 2,5-bis(2-pyridyl)-1-phenylphosphole four isomers are obtained, the 1H NMR spectrum at low temperature indicates that the phosphole ligand may occupy pseudoaxial and equatorial sites at one of the osmium atoms bearing the bridging hydride. The reaction of [Os3(CO)10(CH3CN)2] with cyanoethyldiphenylphosphine affords mono- and bis(phosphine)-substituted clusters. The X-ray crystal structure of the monosubstituted [Os3(CO)11(η1-PC15H14N)] (3) derivative is discussed. The dynamic behavior observed for [Os3(CO)10(η1-PC15H14N)2] (4) is studied by variable-temperature 1H and 31P{1H} NMR spectroscopy. The latter studies show a mixture of two geometric isomers, which are in dynamic equilibrium at room temperature where the 1,2-trans–trans isomer (4a) is favored, whose molecular structure has been determined by X-ray crystallography.

International audience; We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P-containing PAHs exhibit properties expected for an emitter in white organic light-emitting diodes (WOLEDs).

International audience; The straightforward synthesis of new supramolecular metallacycles having a 'pseudo double-paracyclophane' structure is presented. They are obtained from the reaction of a pre-assembled Cu(i) bimetallic precursor bearing short intermetallic distances with cyano-capped homoditopic π-conjugated linkers having flexible central cores.

International audience; Bulk response: Following the development of conjugated polymers that sense ions or neutral molecules, the first π-conjugated polymer which is capable of detecting elemental chalcogens is presented. Individual reactions at the phosphole moieties (see picture) result in macroscopic responses of the bulk polymer.

Redox-basierte Chemotherapie: Die irreversible Hemmung der humanen Glutathion-Reduktase resultiert in einem einmaligen S-AuI-S-Strukturmotiv, das kristallographisch charakterisiert wurde. Eine kinetische Analyse der schnellen und effektiven Hemmung von Redoxenzymen sowie DNA-Wechselwirkungsstudien, ergänzt durch Zellproliferationstests, belegen das chemotherapeutische Potenzial von Phosphinmetallkomplexen

2-(2-Pyridyl)-2-phospholenes are efficient ligands for the palladium-catalyzed telomerization of isoprene with diethylamine. Good selectivities for the tail-to-head or tail-to-tail aminoterpenes are achieved on optimization of the ligand substituents and of the reaction conditions, such as the nature of the catalyst precursor and of the solvent. Moreover, excellent catalytic activities are achieved on photochemical activation or addition of acidic co-catalysts.

The synthesis of mono- and 1,1‘-diphosphaferrocenes bearing thienyl or phenyl substituents at the PCα carbon is described. Monophosphaferrocenes can be obtained using a “one-pot” procedure involvin...

In this work we study three homologues of terthiophene in which the innermost sulphur atom has been replaced by a phosphorous one, namely, 2,5-bis(2-thienyI)phospholes. This strategy pursuits to improve the optical and electronic properties of oligomers derived from thiophene by means of the modulation of their conjugational properties. The assignment of the Raman bands of the phosphole derivatives and their correlation among the series of molecules allows to compare their electronic structures with that of the thiophene counterparts. We have found a disruption of the whole electronic structure on passing to the phospholes, which can be in agreement with the already well known lacking of aromatic character of phosphole as compared with thiophene. Raman spectroscopy also proves effective in addressing σ-π conjugation between π-chromophorcs of a dimer connected through a P-P bond in neutral state.

La synthese et les proprietes de systemes π-conjugues lineaires incorporant des cycles phospholes sont decrites. Des oligomeres a,a'-(phosphole-aryl) de structures bien definies presentent de faibles ecarts HO-BV et leurs proprietes optiques et electrochimiques peuvent etre modulees a la suite de modifications chimiques impliquant l'atome de phosphore. Ces chromophores organophosphores π-conjugues peuvent s'associer a des ions metalliques pour former des complexes mono- ou dinucleaires. Les proprietes specifiques de ces complexes en font des materiaux attractifs pour les diodes electroluminescentes ainsi que pour des dispositifs actifs en optique non lineaire.

The synthesis and electronic properties of new linear organic π-conjugated systems incorporating phosphole rings are described. Well defined α,α′-(phosphole-thiophene) oligomers possess low HOMO–LUMO gaps and their optical and electrochemical properties can be tuned via chemical modifications of the P-atoms. The physical properties of these compounds make them valuable materials for OLED’s. The coordination ability of phosphole-based dipoles has been exploited for the synthesis of efficient multipolar NLO-phores. Lastly, phospholes have been used for the synthesis of assemblies exhibiting through-bond interaction between two π-systems via P–P σ-skeletons.

The homodimeric flavoprotein glutathione reductase (GR) is a central player of cellular redox metabolism, connecting NADPH to the large pool of redox-active thiols. In this work, the inhibition of human GR by a novel gold-phosphole inhibitor (GoPI) has been studied in vitro. Two modes of inhibition are observed, reversible inhibition that is competitive with GSSG followed by irreversible inhibition. When approximately 1 nm GoPI is incubated with NADPH-reduced GR (1.4 nm) the enzyme becomes 50% inhibited. This appears to be the most potent stable inhibitor of human GR to date. Analyzing the monophasic oxidative half-reaction of reduced GR with GSSG at pH 6.9 revealed a K(d)((app)) for GSSG of 63 microm, and a k((obs)max) of 106 s(-1) at 4 degrees C. The reversible inhibition by the gold-phosphole complex [{1-phenyl-2,5-di(2-pyridyl)phosphole}AuCl] involves formation of a complex at the GSSG-binding site of GR (K(d) = 0.46 microm) followed by nucleophilic attack of an active site cysteine residue that leads to covalent modification and complete inactivation of the enzyme. Data from titration spectra, molecular modeling, stopped-flow, and steady-state kinetics support this theory. In addition, covalent binding of the inhibitor to human GR was demonstrated by mass spectrometry. The extraordinary properties of the compound and its derivatives might be exploited for cell biological studies or medical applications, e.g. as an anti-tumor or antiparasitic drug. Preliminary experiments with glioblastoma cells cultured in vitro indicate an anti-proliferative effect of the inhibitor in the lower micromolar range.

The synthesis of Pd(II) complexes 2a,c‘, bearing 2-(2-pyridyl)phosphole ligands which act as P,N chelates, is described. Ligands featuring a pendant pyridyl group spontaneously evolve to the corresponding 2-pyridyl-2-phospholene derivatives in the coordination sphere of Pd(II). This isomerization is a stereoselective process, the stereochemistry of the resulting derivatives 3a,a‘ being established by X-ray diffraction studies. The isomerization of ligands lacking pendant pyridyl groups was accomplished by adding pyridine to the reaction media. High yields were achieved under very mild conditions for ligands possessing different substitution patterns. Multinuclear NMR spectroscopic data and X-ray diffraction studies showed that the stereoselectivity of the process is preserved under these new reaction conditions. The transformation did not occur with free 2-(2-pyridyl)phospholes, even at high temperatures in the presence of pyridine. DFT calculations confirmed that coordination to a Pd(II) center is requir...

2-(2-Pyridyl)phospholes have been evaluated as ligands for the nickel-catalyzed oligomerization of ethylene. Under mild homogeneous reaction conditions, high catalytic activities (>15 cycles per second) were recorded. The selectivity depends on the ethylene pressure. At 41 bar, high C 4 fraction contents (until 97%) and high 1-butene selectivities (80% of the C 4 fraction) were reached. This behavior is interpreted as a consequence of the steric hindrance of the intermediate cationic 2-pyridylphosphole nickel hydrides.

To study the ability of σ-P−P skeleton to mediate interaction between π-chromophores, 1,1‘-biphospholes bearing phenyl or thienyl substituents at the 2,2‘ and 5,5‘-position have been prepared and studied. These air-stable derivatives are readily available via a “one-pot” synthesis starting from diynes. Theoretical studies and UV−vis data clearly establish that the two π-systems interact via the σ-P−P bridge. This through-bond interaction results in a lowering of the optical HOMO−LUMO gap of the assemblies. The nucleophilic σ3-P centers of these 1,1‘-biphospholes allow chemical modifications of the σ-bridge. These modifications offer further tuning of the optical properties of the assembly. Electrooxidation of the thienyl-substituted 1,1‘-biphosphole results in electroactive materials characterized by low optical band gap and reversible p-doping.

Nickel(II)–diiminophosphorane complexes combined with alkylaluminum co-catalysts are active for the oligomerization of ethylene under biphasic reaction conditions. As observed in homogeneous phase, the selectivity (dimers vs higher oligomers) is related to the nature of the diiminophosphorane ligands. In 1- n -butyl-3-methylimidazolium organoaluminate ionic liquids, an enhancement of the catalytic activity and convergence of the selectivity are observed upon repeating cycles. These data suggest that organoaluminate anions replace the diiminophosphorane ligands in the coordination sphere of the active nickel species.

An overview of the synthesis and properties of linear organic π-conjugated systems featuring Group 14 and 15 moieties is presented and comparisons made with their better-known hydrocarbon, and nitrogen- and sulfur-containing analogues. The major focus of this review is π-conjugated systems based on heteroles. The unique electronic structure and nature of siloles and phospholes is examined, highlighting the influence of both the ring substituents and the character of the heteroatom on their photophysical properties. The synthesis of a variety of Group 14 and 15 heterole building blocks suitable for the construction of π-conjugated systems is presented. The preparation and physical properties of poly- and oligo-(1,1-silole)s and -(2,5-silole)s, oligo-(2,5-phosphole)s and co-oligomers of silole and phosphole blocks with other electron-rich monomer units, all with extended π-conjugation, are discussed. A brief resume of linear π-conjugated materials that possess heavy Group 15 elements in the polymer backbone is also presented.

Two synthetic routes to Pd(I) dimers that feature a bridging 1-phenyl- and 1-cyclohexyl-2,5-di(2-pyridyl)phosphole ligand, 3 a and 3 b, respectively, are described. The first involves a conproportionation process between Pd(II) and Pd(0) complexes, while the second involves ligand displacement from a preformed Pd(I) dimer. Both routes are operable for 1-phenylphosphole 1 a, whereas the former failed with 1-cyclohexylphosphole 1 b. A mechanistic study revealed that the conproportionation pathway implies a reversible oxidative addition of the P-C(phenyl) bond of Pd(II)-coordinated 1 a to Pd(0) leading to a bimetallic Pd(II) complex 5. The structures of complexes 3 a and 3 b were studied by means of X-ray diffraction. The similarity of these solid-state structures suggests that the bridging mode of the P atom is due to mu-1kappaN:1,2kappaP:2kappaN coordination of ligands 1 a, b. The electrochemical behaviour and UV/Vis absorption properties of complexes 3 a, b are reported. Complex 3 a is inert towards CO, PPh(3) and 1,3-dipoles. It reacted with dimethylacetylene dicarboxylate to give complex 6 as a result of insertion of the alkyne into the Pd-Pd bond. X-ray diffraction studies of complexes 5 and 6 are also presented.

The coordination behaviour of the readily available 1-phenyl-2,5-di(2-pyridyl)phosphole (NPN) toward Ru centres was investigated. Neutral and ionic compounds of formula [RuCl(p-cymene)(NPN)]TfO (TfO=CF3SO3)… (1), [RuCl(p-cymene)(NPN)]BF4 (2), [RuCl(C6Me6)(NPN)]TfO (3), RuCp′Cl(NPN) [Cp′=C5H5 (4), C5Me5 (5)], Ru(C5Me5)(σ1-C8H13)(NPN) (6), RuCl2(NPN)2 (7) and RuClH(cod)(NPN) (cod=1,5-cyclooctadiene) (8) were obtained. Two diastereomers were obtained for 1, 2 and 4, (a, b) while three were found in the case of 8 (a–c). According to NMR spectroscopy, the 2,5-bis(2-pyridyl)phosphole acts as a 1,4-P,N chelate ligand in all cases. This behaviour was confirmed by an X-ray diffraction study performed on complex 1a. Proton transfer studies on complex 8 demonstrated the influence of the molecular structure on the ability to form dihydrogen bridges.

1,2-Diiminophosphoranes 1–4 featuring either ethane, benzene, cyclohexane or 1,2-diphenylethane carbon backbones act as tightly bonded 1,4-chelating ligands towards NiCl2, affording the corresponding paramagnetic complexes 5–8 in high yield. X-Ray diffraction studies performed on compounds 5 and 6 revealed that the conformation of the five-membered metallacycle depends on the rigidity of the carbon backbone. For both complexes, the coordination sphere of the Ni atom is a distorted tetrahedron with bond lengths and angles around nickel similar to those observed for related Ni(II)(α-diimine) complexes. Complexes 5–8 are active for ethylene oligomerisation under mild reaction conditions (0°C, 1.1 bar) upon activation by alkylaluminum derivatives (Et2AlCl or MAO). The nature of the carbon backbone of the 1,2-diiminophosphorane ligands has a profound impact on the selectivity of the catalytic systems. The selectivity for trimers and higher oligomers varies from 10% (pre-catalyst 8) to 81% (pre-catalyst 5). Effects of varying ethylene pressure, temperature and aluminium co-catalyst/nickel ratios with pre-catalyst 6 are reported. Tailoring the reaction parameters has a modest effect on the oligomer distribution but allows quite high catalytic activities to be achieved with turnover frequencies up to 135×103 h−1.

2-(2-Pyridyl)phospholes bearing phenyl or cyclohexyl substituents on the phosphorus atom and 2-pyridyl, phenyl, or 2-thienyl groups on the C 5 atom were prepared according to the Fagan-Nugent route. They reacted with (cod)PdClCH 3 , giving rise to stable complexes 3a-c and 3a'-c' as single diastereoisomers in excellent yields. An X-ray diffraction study performed on complex 3b featuring a 1-phenyl-2-(2-pyridyl)phosphole ligand revealed a cis configuration of the phosphorus atom and the methyl group. The geometry of the coordinated P atom is highly distorted due to the rigidity of the 1,4-P,N chelate backbone. Complexes 3a,a', featuring 2,5-bis(2-pyridyl)phosphole ligands, display fluxional behavior. NMR studies revealed an intramolecular exchange between the pendant and coordinated pyridyl groups, showing that 2-(2-pyridyl)phospholes can behave as hemilabile ligands. Treatment of complexes 3a-c and 3a'-c' with 1 equiv of AgSbF 6 in CH 3 CN afforded the corresponding cationic derivatives 4a-c and 4a'-c' as single diastereoisomers. Complexes possessing no pendant pyridyl moiety are air-stable solids that can be isolated in high yield. They are active for the copolymerization of ethylene and CO in CH 2 Cl 2 , whereas complex 4a, bearing the 2-(2-pyridyl)phosphole ligand 2a, is reduced quantitatively to give the dinuclear [Pd 2 (2a) 2 ] 2 + complex 6. The catalytic activities obtained with complexes 4b,c and 4b',c' are among the highest obtained with P,N chelates. The substitution pattern of the 2-(2-pyridyl)-phosphole ligands has an impact on the productivity of the Pd catalysts. P-cyclohexylphospholes are more efficient ligands than their P-phenyl analogues. Complex 4c, featuring a 2-(2-pyridyl)-5-(2-thienyl)phosphole ligand, catalyzed the copolymerization of CO and norbornene at 85 °C, affording oligomers with a narrow molecular weight distribution. In methanol, the cationic palladium methyl complex 4c afforded the bis-chelate [Pd(2c) 2 ] 2 + complex 5, which has been characterized by an X-ray diffraction study. Although the geometry around the palladium atom is distorted, the metric data of complex 5 are similar to those of 3b.

2,2′-Di[2-(5-(2-pyridyl)phospholyl)]thiophene ( 2a ) has been obtained in 63% yield via the Fagan–Nugent's route. Derivative 2a possesses an extended π-conjugated system and behaves as a bis( P , N -chelate) towards cationic ( p -cymene)RuCl fragments affording the air-stable complex 3a in 60% yield. A diastereoselective coordination was observed and the solid state structure of the model Ru-complex 2b featuring a related 2-(2-pyridyl)-5-(2-thienyl)phosphole ligand is presented.

The variation in the ratio of the reactants in the supramolecular self-assembly reaction of the bimetallic CuI “U-shaped” molecular clip 1 with the 1,4-dicyanobenzene 3 and the 1,8-anthracene-9,10-carbonitrile 4 “short” ditopic ligand have allowed the observation of new “open” supramolecular assemblies 7 and 8, respectively, in addition to the previously characterized π-stacked supramolecular rectangles 5 and 6, respectively. These new derivatives have been characterized by their solid-state structure obtained by X-ray diffraction on single crystals and by NMR spectroscopy in the case of derivative 7. Depending on the extent of the π system included in the core of the homoditopic linker, different behaviors are observed. In the case of derivative 7 based on the “phenyl” linker 3, a 1:1 1/3 ratio affords the open derivative in a good yield, whereas a 1:0.5 1/4 ratio allows the isolation of derivative 8 in very low yield. These results allow for a tentative analysis of the mechanism that occurs along with the supramolecular self-assembly processes to afford π-stacked supramolecular rectangles.

Phosphole-substituted phosphaalkenes (PPAs) of the general formula Mes*P=C(CH(3))-(C(4)H(2)P(Ph))-R 5 a-c (Mes*=2,4,6-tBu(3)Ph; R=2-pyridyl (a), 2-thienyl (b), phenyl (c)) have been prepared from octa-1,7-diyne-substituted phosphaalkenes by utilizing the Fagan-Nugent route. The presence of two differently hybridized phosphorus centers (σ(2) ,λ(3) and σ(3) ,λ(3)) in 5 offers the possibility to selectively tune the HOMO-LUMO gap of the compounds by utilizing the different reactivity of the two phosphorus heteroatoms. Oxidation of 5 a-c by sulfur proceeds exclusively at the σ(3) ,λ(3) -phosphorus atom, thus giving rise to the corresponding thioxophospholes 6 a-c. Similarly, 5 a is selectively coordinated by AuCl at the σ(3),λ(3) -phosphorus atom. Subsequent second AuCl coordination at the σ(2),λ(3) -phosphorus heteroatom results in a dimetallic species that is characterized by a gold-gold interaction that provokes a change in π conjugation. Spectroscopic, electrochemical, and theoretical investigations show that the phosphaalkene and the phosphole both have a sizable impact on the electronic properties of the compounds. The presence of the phosphaalkene unit induces a decrease of the HOMO-LUMO gap relative to reference phosphole-containing π systems that lack a P=C substituent.

International audience; The discovery and molecular engineering of novel electroluminescent emitting materials is still a challenge in optoelectronics. In this work, we report on the development of new π-conjugated oligomers incorporating a dihydrophosphete skeleton. Variation of the substitution pattern of 1,2-dihydrophosphete derivatives and chemical modification of their P atoms afford thermally stable derivatives which are suitable emitters to construct organic light-emitting diodes. The optical and the electrochemical properties of these new P-based oligomers have been investigated in detail and are supported by DFT calculations. The OLED devices exhibit good performance and current independent CIE coordinates

International audience; Enantiopure mono-cycloplatinated-[8] helicene and bis-cycloplatinated-[6] helicene derivatives were prepared through column chromatography combined with crystallization of diastereomeric complexes using a chiral ancillary sulfoxide ligand. The UV-visible spectra, circular dichroism, molar rotations, and (circularly polarized) luminescence activity of these new helical complexes have been examined in detail and analysed with the help of first-principles quantum-chemical calculations.

International audience; The first helicene-based carbene-osmium complex has been prepared from a vinyl-osmium derivative and this system has been shown to behave as a potential acid-base triggered chiroptical switch.

Two series of 2,5-dipyridyl- and 2,5-dithienylphosphole derivatives containing sigma3- or sigma4-P atoms were prepared, and their optical (UV/Vis absorption, fluorescence spectra) and electrochemical properties were systematically evaluated. These physical properties depend mainly on the natures of the 2,5-substituents and of the phosphorus moiety, and they revealed that these compounds contain extended pi-conjugated systems. Structure-property relationships were established on the basis of these experimental data and ab initio calculations on the parent molecules. The limited aromatic character and low-lying LUMO of the phosphole ring appear to be crucial for achieving a highly delocalised pi system. Electrooxidation of 2,5-dithienylphosphole derivatives affords electroactive films with low optical band gaps. As observed for the corresponding monomers, the optical and electrochemical properties of the polymers can be varied over a wide range by modifying the nature of the phosphorus moiety.

Chiral 1,2-bis[tris(dimethylamino)phosphinimino]cyclohexane (7a, 80% yield), 1,2-bis[tris(dimethylamino)phosphinimino]-1,2-diphenylethane (7b, 74% yield), 1,2-bis[triphenoxyphosphinimino]cyclohexane (9a, 85% yield), and 1,2-bis[triphenoxyphosphinimino]-1,2-diphenylethane (9b, 70% yield) have been prepared using (1R,2R)-1,2-diaminocyclohexane or (1R,2R)-1,2-diphenylethylenediamine and the corresponding phosphine dibromide derivatives (the Kirsanov route). 1,2-Bis[triphenylphosphinimino]cyclohexane (2), 1,2-bis[triphenylphosphinimino]-1,2-diphenylethane (3), and 1,2-diiminophosphoranes 7b and 9b reacted with [Pd(η3-C3H5)Cl]2 in the presence of a silver salt in CH2Cl2 at room temperature to afford the cationic complexes 10 (81% yield), 11 (84% yields), 15 (78% yield), and 16 (74% yield), respectively. According to the same general procedure, palladium complexes [(η3-PhCHCHCHPh)(2)Pd]TfO (13, 88% yield) and [(η3-PhCHCHCHPh)(3)Pd]TfO (14, 86% yield) have been prepared. Single-crystal X-ray diffraction studies ...

The dilithium salts of N-methyl-N′,N′′-bis(diisopropyl)- and -(trimethylsilyl)-diethylenetriamine 1a,b react with SnCl2 affording the corresponding stannylenes 2a,b in 60 and 80% yield, respectively. Compound 1b also reacts with BiCl3 to give the bismuth chloride 5 (90% yield). Derivatives 2b and 5 have a symmetrical bicyclic structure and are monomeric both in solution and in the solid state. When 2b is treated with BiCl3 or PCl3, an oxidation reaction leads to the hypercoordinated tin(IV) dichloride 3 (58% yield), or a transmetallation gives rise to the oniophosphane 4 (95% yield), respectively. Transmetalation reactions also occurred when 5 was treated with AlCl3, GaCl3 or SnCl2 affording the corresponding aluminum chloride 6 (81% yield), gallium chloride 7 (38% yield) or tin dichloride 3 (38% yield). The observed reactivity for 2 and 5 is compared to that reported for Veith's stannylene or bismuth chloride.